'This isn't going to go by. It will be sorted. Them that did it will know this'

Among the bunches of flowers and cards piled up outside the small flat where Billy Cox, 15, was shot and killed, a friend had scrawled a telling message yesterday: "To Remer: Nuff Luv. All da mandem will miss u heaven's new fallen soldier".

The words, a few centimetres high and written in black pen, gave an insight into the final months of the teenager who, this week, became the latest victim of south London's escalating gun wars. Billy, who was shot at point blank range at his home in Clapham on Wednesday, was allegedly involved with one of the gangs in his area, the Clap Town Kids. Yesterday a website dedicated to Billy, whose street name was Remer, showed a video of the teenager rapping with friends. Underneath, posts praised the "fallen soldier". "I hope da mandem hu dne it read all des messeges so dai knw dat remer...was loved by all," read one.

On the Fenwick estate, where Billy died, teenagers said mandem was slang for gang and warned Billy's death would have repercussions. "This isn't going to go by," said one. "It will be sorted. Them that did this will know that."

Yesterday the extent of Billy's involvement in south London's gang wars in which three teenagers have been shot and killed in 11 days remained unclear.

Many friends insisted yesterday that he was an innocent victim. Others said he had offended a member of another gang, or that he owed money for drugs.

What was not in doubt was the growing number of teenage gang members who routinely carry and use guns on south London's estates. Some reports suggested that members of the Clap Town Kids had clubbed together to buy a gun to share.

"Getting hold of gun round here is as easy as going into a McDonald's and getting a McChicken sandwich," a 16-year-old on the estate told the Guardian yesterday. "If I had the money I could make a phone call and get a gun now... It wouldn't cost [as much as £150], you could ask anyone to borrow a gun... hey would let you."

Family

The Clap Town Kids, centred around the Fenwick estate, are part of a web that crisscrosses south London, including the PDC [Poverty Driven Children] in Brixton, Ghetto in Lewisham, and the Blood Set in Streatham. One former member of the Clap Town Kids said yesterday that gangs were as important as families to many teenagers. "They [gang members] are like brothers - they protect each other through thick and thin."

Some residents said Billy had been killed after a text message argument, and yesterday a former member of the PDC told the Guardian how a seemingly small slight could trigger a devastating response. "It could easily have been that he had done something little, and that sparked this," said Ryan, 19, from Brixton. "These gangs operate on respect; if someone feels that they have been dissed, they have to act - or it's them that looks bad, and they are seen as weak."

Although Billy was serving a 12-month supervision order for burglary and was on a curfew, many residents said he had only started getting into trouble in the last year or so.

But Ryan said that was not unusual. "When you get to 14 and 15 and you are living in these places, you have to make a decision about which way you are going to go - it's what I had to do," he said.

"It's OK sitting here asking why do we get involved, but if you are there and you don't, then you are nothing.

"You get robbed and beaten up, you get no respect if you are not in a gang - whether its on the bus, or in the street. Even at school and from the police and from the newspapers you get more attention if you are part of it."

Attacks

Yesterday Mercedes, 19 who grew up around the Ghetto gang in New Cross, Lewisham, said it was easy for teenagers to be drawn towards gangs. "I tried everything I could think of to get in [to the Ghetto gang]," she said.

"I would attack people in the street if I thought the 'olders' [senior gang members] were watching, or rob people, or try and go with the guys.

"When you are up close, it's the gang that matters; you are not interested in jobs or school or anything, you just need to get their respect." She said that once the gang members reached 14 or 15, they were usually selling drugs and using the guns themselves. "That is the most dangerous time, cos it's when people have to prove themselves," she said.

"At that time you earn your reputation; and if someone does something to disrespect you, then you have to act or not - it's that pathetic; but when you are in it, it's real."

She said most of the gangs were made up of teenagers, but older men, who had often been in prison, were still pulling the strings.

A 16-year-old, who left the Clapham gang after his friend was killed, agreed, saying older gang leaders were role models.

"They are the nicest people and the most dangerous," he told the Guardian. "They control everything, they can tell you to sell this, or kill that person."

Yesterday residents on the Fenwick estate were trying to understand exactly why Billy had been taken from them. On the walls and stairwells friends had added RIP to his graffiti tag.

But as the media vans began to pack up and move on, a 16-year-old who had just laid flowers outside Billy's flat was already looking forward.